The possible role of estrogen in the incidence of temporomandibular disorders

Association between estrogen receptors polymorphisms and temporomandibular joint disorders: A systematic review

OBJECTIVES

This systematic review aimed to investigate the association between genetic polymorphisms in estrogen receptor alpha (ERα) and beta (ERβ) and the presence and severity of temporomandibular disorders (TMDs).

MATERIALS AND METHODS

A comprehensive search was conducted in PubMed, Scopus and Web of Science on October 19, 2024, without language or time restrictions. Studies were included if they were cross-sectional, case-control, or cohort designs and reported data on ER-polymorphisms and TMDs, diagnosed using validated criteria. Two independent reviewers screened the results to identify eligible studies. Data were extracted and synthesized narratively due to high heterogeneity across included studies, with a subgroup analysis performed to evaluate the influence of sex. The risk of bias was assessed using the Joanna Briggs Institute's critical appraisal tools.

RESULTS

The search identified 277 articles, of which 8 studies met the inclusion criteria. Seven were case-control and two cross-sectional studies. The most commonly investigated ER polymorphisms were ESR1 (Pvu II and Xba I) and ESR2 (rs1676303). Some studies identified associations between specific polymorphisms and TMD-related pain or joint conditions, although results varied across different populations and subtypes of TMDs.

CONCLUSIONS

The findings suggest potential associations between specific ERα and ERβ polymorphisms and TMD risk, particularly in women. However, inconsistencies across studies underscore the need for prospective and larger studies to confirm these genetic links and clarify their clinical significance.

SYSTEMATIC REVIEW REGISTRATION

CRD42024581266.

Hormone replacement therapy did not alleviate temporomandibular joint inflammatory pain in ovariectomized rats

This study had the aim of examining the relationships between variations in estrogen levels resulting from ovariectomy, and estrogen hormone replacement therapy (HRT) in rats subjected to an orofacial inflammatory pain model. Eighty adult female Wistar rats were initially divided into 2 groups: Sham or ovariectomy (OVX-D1). Seven days later (D7), the rats were subjected to an unilateral infiltration of Freund's Complete Adjuvant (CFA) or saline solution into the right temporomandibular joint (TMJ). Then, rats received 17β-estradiol (28 µg/kg/day) or placebo for 21 days (D10-D31). Nociception was evaluated by the von Frey (VF) and the Hot Plate (HP) tests, and depressive-like behavior by the Forced Swimming (FS) test. On D32 all rats were euthanized and serum, hippocampus and brainstem were collected. The CFA groups presented a mechanical hyperalgesia until day 21 (p ≤ 0.05). No differences were observed among groups in the HP (p = 0.735), and in the immobility and swimming time of the FS (p = 0.800; p = 0.998, respectively). In the brainstem, there was a significant difference in the TNF-ɑ levels (p = 0.043), and a marginal significant difference in BDNF levels (p = 0.054), without differences among groups in the hippocampal BDNF and TNF-ɑ levels (p = 0.232; p = 0.081, respectively). In conclusion, the hormone replacement therapy did not alleviate orofacial pain in ovariectomized rats. However, there is a decrease in brainstem TNF-ɑ levels in the animals submitted to both models, which was partially reverted by HRT.

Risk factors for temporomandibular disorders: a systematic review of cohort studies

OBJECTIVE

A systematic review was performed to synthesize and identify risk factors involved in TMD onset.

STUDY DESIGN

Electronic searches were conducted in PubMed, Web of Science, Scopus, Embase, PsyInfo and Lilacs databases, as well as in three gray literature databases (Google Scholar, ProQuest and Open grey). The studies were blindly assessed by two reviewers and selected by a pre-defined eligibility criterion. Risk of bias of included studies was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Cohort Studies. Grading of Recommendations Assessment, Development and Evaluation (GRADE) was evaluated for most related factors.

RESULTS

Twenty-one cohort studies were included. Significant factors were female gender, symptoms of depression and anxiety, perceived stress, sleep quality, symptoms of obstructive sleep apnea and presence of any comorbidity, such as Irritable Bowel Syndrome, lower back pain, headache frequency, tension-type headache, migraine and mixed headache. Moreover, high estrogen and low testosterone levels in utero, greater pain perception, jaw mobility pain, pain during palpation, orofacial anomalies, as well as extrinsic and intrinsic injuries were also significant.

CONCLUSIONS

Several factors seems to be involved in TMD onset, however, more studies with standardized methodology are necessary to confirm these findings.

Exercise therapy in postoperative patients with temporomandibular joint internal derangement: A systematic review

OBJECTIVE

Postoperative patients with temporomandibular joint internal derangement (ID) often have problems such as limited mouth opening and pain. Exercise therapy can be advantageous for improving the recovery of patients following surgery. However, there is continuing discussion on the precise aspects of the exercise program, including the optimal timing, length, intensity, and use of assistive equipment. Hence, this study aimed to incorporate pre-existing exercise treatment regimens and investigate their impact.

METHODS

Publications that detailed the clinical treatment of patients with temporomandibular joint ID who received postoperative exercise therapy interventions were included. Nine databases were searched until October 1st, 2023. The JBI critical appraisal tools were used to assess the methodological quality of the included studies.

RESULTS

Five studies were finally included for subsequent analysis; two were randomised controlled studies, and three were quasi-experimental. Exercises suitable for such patients encompass vertical, transverse, and horizontal stretching, among which vertical stretch can be divided into active and passive movements. The start time ranged from the first to the fifth week after surgery, with a duration of 1-6 months. Although the data in the studies could not be integrated and further analysed, preliminary results showed that maximum mouth opening and pain in patients improved significantly. The therapeutic effect of combining three exercise methods was best and was related to patient compliance.

CONCLUSION

Exercise therapy positively affects postoperative rehabilitation in patients with temporomandibular joint ID. It is proposed that targeted, comprehensive studies be conducted to provide a basis for designing more sophisticated exercise therapy regimens and further confirm its curative effect.

Mechanisms Underlying Sex Differences in Temporomandibular Disorders and Their Comorbidity with Migraine

Sexual dimorphism in temporomandibular disorders (TMDs) and their comorbidity with migraine are important phenomena observed in clinics. TMDs are the most prevalent orofacial pain conditions with jaw joint and masseter muscle dysfunction. Migraine is the predominant headache commonly associated with TMDs. Women much more often suffer from this orofacial pain than men. However, currently, there is no gender-specific therapy for such pain conditions. Understanding the pathophysiological mechanisms behind sex differences in TMDs as well as their comorbidity with migraines is essential for developing novel approaches for gender-specific treatment of TMDs and related orofacial pain comorbidity. In this review, we summarize recent research progress regarding sex differences in TMDs, focusing on the underlying mechanisms including craniofacial anatomy, hormonal regulation, and roles of opioids, transient receptor potential channels, and endocannabinoid systems. We also discuss the mechanisms of comorbid TMDs and migraine. The information covered in this review will provide mechanistic insights into sex differences in TMDs and their comorbidity with migraine, which could aid in developing effective treatment strategies for the overlapping orofacial pain condition.

A mechanoluminescent material, ZnS:Mn,Li, with enhanced brightness for visualizing dental occlusion

Mechanoluminescent materials are characterized by high luminescence intensity, high repeatability, no external voltage activation, and a good linear relationship between stress and mechanoluminescence intensity within a certain range. Therefore, mechanoluminescent materials have attracted increasing attention from researchers in the fields of stress sensing, encryption and anti-counterfeiting, structural health monitoring, energy-saving lighting, intelligent wearable devices, and other fields. In this study, ZnS:Mn powders with different Mn2+ ratios and different ion doping were synthesized by a high-temperature solid-phase reaction, and the synthesis of various materials was characterized. Then, the optimal mechanoluminescence effect of the ZnS:1%Mn,1%Li material was obtained. The photoluminescence intensity of ZnS:1%Mn,1%Li was 16.7 times higher than that of the sample without doping with Li+, and the mechanoluminescence intensity was 1.64 times higher. Finally, polyethylene terephthalate (PET) film was combined with ZnS:Mn,Li mechanoluminescent powders to prepare flexible three-layer composite film. Based on this, a feasible strategy for the detection of temporomandibular disorders was proposed. The composite film is easy to use, economical, and safe, and has good mechanoluminescent performance, which has potential application value in the field of occlusal force detection and visualization.

Exploring the effect of disc displacement on the risk and severity of condylar erosion in adult temporomandibular disorder patients: A CBCT and MRI study

OBJECTIVE

The objective of the study was to investigate the relationship between types of disc displacement (DD) diagnosed by magnetic resonance imaging (MRI), and the risk (presence or absence) and severity of condylar erosion (CE) graded using cone-beam computed tomography (CBCT) in adult Temporomandibular disorders (TMD) patients.

METHODS

A total of 353 TMD patients (283 females, 70 males) underwent MRI scans to categorise DD as normal (NA), anterior displacement with reduction (ADDR), or anterior displacement without reduction (ADDNR). CE severity was graded on a scale of 0-3 (absence, mild, moderate or severe) using CBCT. To establish the plausibility and cut-off points for CE diagnosis, the severity of CE was then further divided into three classifications: Grade 0 versus 1 + 2 + 3; Grades 0 + 1 versus 2 + 3; Grades 0 + 1 + 2 versus 3. Logistic regression analysis was performed, adjusting for age, gender and joint correlation.

RESULTS

ADDNR significantly increased the risk of CE compared with NA (OR = 10.04, 95% CI: [6.41, 15.73]) and showed a significant increase in CE severity across all classifications (ORs = 10.04-18.95). The effects of ADDNR were significant in both genders (p < .001) and had a greater impact in females. ADDR was predominantly associated with mild CE.

CONCLUSIONS

ADDNR significantly increased the risk and severity of CE independent of gender when compared to NA, whereas ADDR was mainly associated with mild CE. Slight cortical discontinuity may represent a subclinical diagnosis requiring further investigation.

Pregnancy related factors and temporomandibular disorders evaluated through the diagnostic criteria for temporomandibular disorders (DC/TMD) axis II: a cross sectional study

INTRODUCTION

Temporomandibular disorder (TMD) is a multifaceted condition impacting the chewing system, with its frequency varying across different age groups and showing a higher incidence in women. The involvement of estrogen in TMD has been examined due to the presence of estrogen receptors in the TMJ area. However, the exact effect of estrogen on TMD is complex. During pregnancy, marked by significant hormonal fluctuations, the impact on TMD has been hypothesized but remains unclear due to inconsistent results from various studies.

METHODS

In this cross-sectional study, we enrolled 32 pregnant women consecutively. We gathered information on demographics, TMD evaluations (using the Graded Chronic Pain Scale, Jaw Functional Limitation Scale-20, and Oral Behaviors Checklist), and mental health assessments (including Patient Health Questionnaire-9, Patient Health Questionnaire-15, and Generalized Anxiety Disorder-7). We employed descriptive statistics to summarize continuous and categorical data and used t-tests and chi-square tests for comparisons. We also conducted multivariate linear regression, adjusted for demographic factors, to investigate correlations.

RESULTS

The study group mainly consisted of women aged 30-35 (40.6%) and 25-30 (18.8%). Most participants had completed high school (50%) and were married (71.9%). A notable association was found between younger women (under 30) and higher levels of somatic symptoms (p = 0.008) and generalized anxiety (p = 0.015). Women in their second trimester showed lower severity of somatic symptoms (p = 0.04). A significant link was also observed between depression severity and somatic symptom severity (p = 0.01). However, we found no significant correlations with other TMD-related health aspects.

DISCUSSION

Our study identified significant associations between psychosomatic and psychological symptoms with variables like age and pregnancy trimester in pregnant women. However, it notably failed to establish a clear relationship between pregnancy-related factors and the severity of temporomandibular disorders (TMD). More comprehensive studies with larger participant pools are necessary to further validate and expand these findings.

Is core stability training effective in temporomandibular disorder? A randomized controlled trial

OBJECTIVES

This study investigated the effect of core stability training on pain, function, quality of life, and posture in individuals with temporomandibular disorder.

MATERIALS AND METHODS

Participants were divided into the following: the core stability group and the control group. For pain assessment, the Graded Chronic Pain Scale 2.0; for function, the 20-item Jaw Functional Limitation Scale (JFLS-20); for oral health-related quality of life, Oral Health Impact Profile-14 (OHIP-14); and for posture assessment, the New York Scale were used. Rocabado exercises were applied to the control group. Additionally, spinal stabilization exercises were applied for the core stability group for 6 weeks.

RESULTS

Both types of exercise contribute positively to the quality of life associated with oral health. Rocabado exercise provided a significant change in Chronic Pain Intensity and Disability Score.

CONCLUSION

Rocabado exercise and core stability training, implemented with Rocabado, provide significant changes in pain values. When evaluated in terms of function, no significant difference was found in both exercise programs.

CLINICAL RELEVANCE

Core stability training with Rocabado provides significant changes.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04755621.

Accurate Diagnosis and Treatment of Painful Temporomandibular Disorders: A Literature Review Supplemented by Own Clinical Experience

Introduction

Temporomandibular disorders (TMD) is a multifactorial group of musculoskeletal disorders often with combined etiologies that demand different treatment plans. While pain is the most common reason why patients decide to seek help, TMD is not always painful. Pain is often described by patients as a headache, prompting patients to seek the help of neurologists, surgeons, and ultimately dentists. Due to the unique characteristics of this anatomical area, appropriate diagnostic tools are needed, as well as therapeutic regimens to alleviate and/or eliminate the pain experienced by patients. Aim of the Study. The aim of this study is to collect and organize information on the diagnosis and treatment of pain in TMD, through a review of the literature supplemented by our own clinical experience. Material and Methods. The study was conducted by searching scientific databases PubMed, Scopus, and Google Scholar for documents published from 2002-2022. The following keywords were used to build the full list of references: TMD, pain, temporomandibular joint (TMJ), TMJ disorders, occlusal splint, relaxing splints, physiotherapy TMD, pharmacology TMD, natural therapy TMD, diagnostic criteria for TMD, and DC/TMD. The literature review included 168 selected manuscripts, the content of which was important for pain diagnosis and clinical treatment of TMD.

Results

An accurate diagnosis of TMD is the foundation of appropriate treatment. The most commonly described treatments include physiotherapy, occlusal splints therapy, and pharmacological treatment tailored to the type of TMD.

Conclusions

Based on the literature review and their own experience, the authors concluded that there is no single ideal form of pain therapy for TMD. Treatment of TMD should be based on a thorough diagnostic process, including the DC/TMD examination protocol, psychological evaluation, and cone beam computer tomography (CBCT) imaging. Following the diagnostic process, once a diagnosis is established, a treatment plan can be constructed to address the patient's complaints.

The Role of Sex Hormones in Pain-Related Conditions

Millions of people are affected by pain-related conditions worldwide. Literature has consistently shown that each individual experiences and perceives pain in a unique manner due to biological, environmental, and cultural factors in which they have been raised. It has been established that biological males and females perceive pain differently and that it may be partially explained by their distinct hormonal profiles since birth, which are only further magnified during puberty. For biological males, high levels of testosterone have shown to increase their pain threshold; and for biological females, estrogen fluctuations have shown to increase pain intensity and perception. However, sex hormones have not been studied in the context of pain treatment or their impact on biochemical pathways involved in pain perception. For this purpose, the transgender community serves as a unique population to investigate the impact of hormone replacement therapy on molecular pathways involved in the perception of pain. The purpose of this review is to explore the biochemistry of hormone replacement in transgender patients who also have other pain-related conditions such as headaches, fibromyalgia, temporomandibular myalgia, and visceral pain.

Craniofacial Morphology of Temporomandibular Disorder Patients with Different Disc Positions: Stratifying Features Based on Sex and Sagittal Skeletal Pattern

Disc displacement (DD) appears in the majority of temporomandibular disorder (TMD) patients. The correlation between craniofacial morphology and different disc positions has been underlined, while the craniofacial morphological differences based on sex and sagittal skeletal pattern stratification have been insufficiently studied. In this study, 304 patients with TMD complaints were included and classified into normal position, disc displacement with reduction (DDwR) and disc displacement without reduction (DDwoR) groups according to magnetic resonance imaging. A total of 24 cephalometric measurements, covering the cranial base, vertical relationship, sagittal relationship, mandible position and morphology, and dental relationship, were assessed using lateral cephalograms. A stratified analysis was performed based on the sex and sagittal skeletal pattern. Overall, DD patients had distinctive craniofacial morphological features. The posterior cranial base length and mandibular arc angle were statistically different only in females, while the Y-axis angle, occlusal plane angle and sella nasion point A angle (SNA) might be unique features in males. Skeletal class II had the most statistically different measurements compared to the others. Differences in the Frankfort mandibular incisor angle (FMIA) and saddle angle were especially displayed in skeletal class III patients. The sex and skeletal sagittal pattern could affect the morphological differences in TMD patients with different disc positions.

Comparison of the effectiveness of soft and hard splints in the symptomatic management of temporomandibular joint disorders: A randomized control study

AIM

Splint therapy is a well-established modality in the management of temporomandibular joint disorders (TMDs). We aimed to evaluate and compare the effectiveness of hard and soft splints in the symptomatic management of TMDs using the modified Helkimo index.

METHODS

This study included 91 patients diagnosed with TMDs. Participants were randomly allocated into two treatment groups. All these patients were treated by hard or soft stabilization splint therapy. Group 1: hard splint group, n = 42 (mean age - 31.62 ± 8.5 years), 10 males and 32 females; group 2: soft splint group, n = 49 (mean age - 32.86 ± 9.06 years), 13 males and 36 females. The anamnestic and clinical dysfunction component of the modified Helkimo index was used to evaluate the outcomes at baseline (T₀ ), first month (T₁ ), and third month (T₂ ).

RESULTS

Symptoms such as clicking of the joints, temporomandibular joint (TMJ) pain and muscle pain showed improvement in both groups (P < .05). Restriction and deviation of mouth opening did not show significant improvement in either group. The patients who underwent hard splint therapy showed an early improvement of symptoms at T₁ (P < .05). However, there was no statistical difference in the improvement of symptoms between hard and soft splints at T₂ .

CONCLUSION

Both hard and soft stabilization splints were effective in the symptomatic management of TMDs. However, hard splints provide an earlier reduction of symptoms.

Effects of Occlusal Splints on Spinal Posture in Patients with Temporomandibular Disorders: A Systematic Review

There is still a gap in the scientific knowledge on the linkage between craniofacial structure and spinal postural control in temporomandibular disorder (TMD) patients. This systematic review aimed to assess the role of occlusal splints on spinal posture of TMD patients. PubMed, Web of Science, and Scopus were systematically searched from inception until 5 January 2022 to identify observational studies with a longitudinal study design presenting: patients with diagnosis of TMD according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD); occlusal splint therapy as intervention; postural assessment as outcome. Out of 133 records identified, 104 were suitable for data screening, and only 7 articles were included satisfying the eligibility criteria. We found that occlusal splints might have a positive effect on posture in TMD patients, albeit there is little evidence of appropriate investigation for postural assessment. This systematic review suggested that the occlusal splint might be considered a non-invasive therapeutic approach for patients with TMD. However, the low number of studies with high-quality methodology in these patients showed an urgent need for further research using combined force platform stabilometry and kinematic evaluation of the spine to investigate the impact of occlusal splints on posture.

Increased Risk of Temporomandibular Joint Disorder in Osteoporosis Patients: A Longitudinal Study

BACKGROUND

The objective of this study was to investigate the risk of temporomandibular joint disorder (TMD) in patients with osteoporosis.

METHODS

Data from the Korean National Health Insurance Service-Health Screening Cohort from 2002 to 2015 were collected. Participants ≥ 40 years old were enrolled, and the history of osteoporosis was evaluated. The 62,328 osteoporosis patients were matched for age, sex, income, and region of residence with 62,328 control participants. The occurrence of TMD was assessed in both the osteoporosis and control groups during the follow-up period. Stratified Cox proportional hazard analyses for TMD were conducted for the osteoporosis and control groups. The hazard ratios (HRs) of osteoporosis for TMD were further analyzed by age and sex subgroups.

RESULTS

A total of 1.2% (725/61,320) of the osteoporosis patients and 0.6% (339/61,320) of the control participants had TMD (P<0.001). Osteoporosis was associated with an elevated HR of TMD (adjusted HR=1.96, 95% CI=1.72-2.23, P<0.001). Among the age and sex subgroups, the < 60-year-old mal\e group demonstrated an adjusted HR of osteoporosis for TMD as high as 4.47 (95% CI=1.17-17.12, P=0.029). Other age and sex subgroups also showed a higher HR for TMD associated with osteoporosis (adjusted HR=2.30, 95% CI=1.90-2.78, P<0.001 for the ≥ 60-year-old female group).

CONCLUSION

Osteoporosis was related to a higher risk of TMD in the adult population. A prominent association of osteoporosis with TMD was noted in middle-aged men and older women.

Association of temporomandibular disorders with pain sensitivity: A cohort study

BACKGROUND

Pain related to temporomandibular disorders (TMD) can be linked with multiple site pain (MSP), and may associate with increased pain sensitivity, more frequently among women than men. The aim of the study was to examine the associations of pressure pain threshold (PPT) and tolerance (PPTo) with TMD and associated MSP in the Northern Finland Birth Cohort 1966 (NFBC1966) study.

METHODS

Altogether 1961 NFBC1966 subjects attended clinical medical and dental examination at the Institute of Dentistry, University of Oulu in 2012-2013. Clinical examinations were carried out using a modified Diagnostic Criteria for TMD protocol (DC/TMD). MSP was defined based on questions regarding body pain sites. Additionally, PPT and PPTo were assessed using algometer measurements. Mann-Whitney U-test and Tobit regression models were used to analyse associations between TMD sub-diagnoses, MSP, PPT and PPTo, stratified by sex. Further models were adjusted with anxiety and depressive symptoms, which were assessed using Hopkins Symptom Checklist-25 (HSCL-25) and two-way interaction terms.

RESULTS

Among females, lower PPT and PPTo were associated with myalgia and arthralgia. Among males, lower PPT and PPTo were associated with MSP-linked TMD. Tobit regression analysis showed significantly lower PPT and PPTo values in the myalgia and arthralgia subgroups among female TMD subjects. Among females, disc displacement with reduction had an inverse association with PPT and PPTo. Among males, lower PPTo was associated with degenerative joint disease and MSP-linked TMD.

CONCLUSIONS

The pain regulatory mechanisms behind TMD act differently between the genders as local TMD among females and MSP-linked TMD among males were associated with pain sensitivity.

SIGNIFICANCE

The study shows that there are differences in the associations of painful TMD with pressure pain tolerance, pressure pain sensitivity and MSP between male and female subjects.

Efficacy of occlusal splints in the treatment of temporomandibular disorders: a systematic review of randomized controlled trials

OBJECTIVE

This systematic review aimed to assess the efficacy of occlusal splints in the treatment of temporomandibular disorders (TMDs).

MATERIAL AND METHODS

This systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Four databases (Medline via Pubmed, Web of Science, Embase and Scopus) were searched, the last search was conducted on April 2020. Randomised controlled trials (RCTs) employing the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) or Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) as diagnostic criteria and including occlusal splint as one of the experimental groups were included in the present study. The data from the included studies were extracted and assessed for risk of bias.

RESULTS

Eleven studies were included. The sample size ranged from 12 to 96 subjects. The male to female ratio was 0 to 25%. The mean length of follow-up was 4 months. Occlusal splint had a positive effect on mandibular movements in all included studies. Seven studies showed a positive effect of occlusal splint on chronic pain reduction and pain intensity, while two others showed improvement of temporomandibular joint clicking sounds and locking of the jaws. Moreover, improvements in mouth opening, depression, and anxiety symptoms, were reported in four studies.

CONCLUSIONS

An occlusal splint can be considered as a non-invasive treatment approach for patients with TMD, especially those with signs and symptoms of restriction of mandibular movement and pain. Moreover, the present findings highlighted an urgent need of a standardised consensus regarding the prognostic evaluation of TMD.

Craniomandibular Disorders in Pregnant Women: An Epidemiological Survey

Temporomandibular joint (TMJ) disorder has been reported to be 1.5 to two times more common in women than men. Such a gender-based difference could be attributed to behavioral, hormonal, anatomical, and psychological characteristics. Physiological hormonal differences between genders could be one of the possible explanations for the higher incidence of temporomandibular disorder (TMD) in women. As the plasma level of certain female hormones increases during gestation, it could be assumed that there is a higher prevalence of dysfunctional signs and symptoms in pregnant women. We performed an epidemiological survey based on screening for TMD in a group of 108 pregnant women and found that 72% of young women reported significant signs of TMJ disorders, 9% of the young women reported mild signs of TMJ disorders, and 19% of the included subjects reported no signs or symptoms of TMD. The presence of estrogen receptors in the temporomandibular joint of female baboons could be the basis of an explanation for the increased prevalence of dysfunction in young women reported in the literature and the high feedback we have seen of joint noises in pregnant women. On the basis of the present findings, it could be assumed that gestation period could represent a risk factor for craniomandibular dysfunctions.

Association between oestrogen receptors and female temporomandibular disorders

Objective: To evaluate if temporomandibular disorders (TMDs) are associated with genetic polymorphisms in ESR1 and ESR2, which are genes encoding oestrogen receptor alpha (ERα) and beta (ERβ). Also, we included an animal model to check if ERα and ERβ are expressed in the temporomandibular joint (TMJ) during adolescence.Materials and methods: A total of 139 teenagers and 93 adults were diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMDs). The DNA was collected and the markers ESR1 and ERS2 were genotyped. Additionally, immunohistochemistry was performed in TMJ tissues from female Wistar rats during puberty. All data were submitted to statistical analysis with confidence interval of 95%.Results: Teenagers presented more disc displacement and arthralgia than adults (p < .05). The genetic polymorphism rs1256049 in ESR2 was associated with disc displacement (p = .040; OR = 10.50/95%CI 1.17-98.74) and arthralgia (p = .036; OR = 7.20/95%CI 1.10-46.88) in adults. The ERα and ERβ are expressed in rat TMJ tissues.Conclusions: We provide evidence that ESR2 is associated with TMD and could be a genetic marker for this condition in adult women. Furthermore, oestrogens receptors are presented in TMJ of adolescent female rats.

Dose-Dependent Clinical, Radiographic, and Histopathologic Changes of 17β-Estradiol Levels Within the Temporomandibular Joint: An Experimental Study in Ovariectomized Dogs

PURPOSE

The aim of this study was to test the hypothesis that the dose of estrogen replacement therapy may have an influence on the clinical, radiographic, and histopathologic changes within the temporomandibular joint (TMJ).

MATERIALS AND METHODS

A prospective experimental study was conducted in 12 mature ovariectomized dogs. Dogs were randomly allocated into 1 of 4 groups (OVX-E0, dogs that did not receive any estrogen replacement therapy; OVX-E0.5, dogs that received 0.15 mg/kg of estradiol; OVX-E1, dogs that received 0.3 mg/kg of estradiol; and OVX-E2, dogs that received 0.6 mg/kg of estradiol); dogs were evaluated clinically for 12 weeks; and contact radiographic and histopathologic examinations of the TMJ were performed just after euthanasia.

RESULTS

Radiographic examination of the TMJ in the OVX-E0 group showed narrowing of the joint space with marginal osteophyte formation along the mandibular condyle. The OVX-E0.5 group showed mild widening of the joint space with no remarkable changes within the mandibular fossa or condyle. The OVX-E1 group was free of radiographic changes within the TMJ. High doses of estrogen in the OVX-E2 group showed marked flattening of the mandibular condyle and fossa with sclerosis of the subchondral bone. Histopathologic sections in the OVX-E0 group showed thin compact bone with scanty, less organized lacunae. The OVX-E0.5 group showed compact bone of medium thickness with large osteons and disorganized lacunae. The OVX-E1 group showed thick compact bone with reduced intertubercular spaces and organized lacunae. The OVX-E2 group showed thin bone with reduced trabecular and increased intertrabecular thickness. The collagen content did not change significantly among the 4 groups, whereas its quality changed significantly (P < .05).

CONCLUSIONS

Estrogen dosage is potentially a key regulator of bone metabolism within the TMJ. Estrogen replacement therapy exhibited an inverted U-shaped beneficial effect. Estrogen depletion as well as high doses of estrogen resulted in clinical, radiographic, and histopathologic changes within the TMJ. Estrogen replacement therapy should be prescribed at the optimum dose when indicated as hormonal replacement therapy.

Temporomandibular joint osteoarthritis at Chelechol ra Orrak, Palau

OBJECTIVE

To explore the frequency and severity of temporomandibular joint osteoarthritis (TMJ-OA) and its causative factors in a skeletal assemblage from the prehistoric site of Chelechol ra Orrak, Palau, western Micronesia.

MATERIALS

50 temporomandibular joint surfaces (mandibular condyles and articular eminences), representing a minimum of 22 adult individuals, 17 of which retain teeth.

METHODS

Joint surfaces were macroscopically evaluated for characteristics associated with TMJ-OA and joint morphology. Dental remains were scored for tooth wear and staining.

RESULTS

Nine individuals (40.1 %) displayed lesions typical of TMJ-OA. The strongest associations were between tooth wear and TMJ-OA.

CONCLUSIONS

Indirect effects of parafunctional dental activity appear to be a factor in TMJ-OA frequency at Chelechol ra Orrak. While betel nut chewing may be one of those activities, it does not appear to be solely driving the presence of TMJ-OA.

SIGNIFICANCE

This study highlights the association between a specific parafunctional use of the temporomandibular joint and the potential pathological consequences. It also reinforces the need to carefully evaluate the archaeological context of skeletal remains in order to evaluate specific etiological factors in the presence of TMJ-OA in present and past populations.

LIMITATIONS

Sample sizes are limited in this study. This will increase as excavations continue.

SUGGESTIONS FOR FURTHER RESEARCH

Because dental occlusion appears to be associated with TMJ-OA, focus on dental conditions affecting occlusal patterns, such as third molar agenesis, antemortem tooth loss, and malocclusion, and their relationship to TMJ-OA frequency, are recommended.

Temporomandibular Joint Bioengineering Conference: Working Together Toward Improving Clinical Outcomes

The sixth temporomandibular joint (TMJ) Bioengineering Conference (TMJBC) was held on June 14-15 2018, in Redondo Beach, California, 12 years after the first TMJBC. Speakers gave 30 presentations and came from the United States, Europe, Asia, and Australia. The goal of the conference has remained to foster a continuing forum for bioengineers, scientists, and surgeons and veterinarians to advance technology related to TMJ disorders. These collective multidisciplinary interactions over the past decade have made large strides in moving the field of TMJ research forward. Over the past 12 years, in vivo approaches for tissue engineering have emerged, along with a wide variety of degeneration models, as well as with models occurring in nature. Furthermore, biomechanical tools have become more sensitive and new biologic interventions for disease are being developed. Clinical directives have evolved for specific diagnoses, along with patient-specific biological and immunological responses to TMJ replacement devices alloplastic and/or bioengineered devices. The sixth TMJBC heralded many opportunities for funding agencies to advance the field: (1) initiatives on TMJ that go beyond pain research, (2) more training grants focused on graduate students and fellows, (3) partnership funding with government agencies to translate TMJ solutions, and (4) the recruitment of a critical mass of TMJ experts to participate on grant review panels. The TMJ research community continues to grow and has become a pillar of dental and craniofacial research, and together we share the unified vision to ultimately improve diagnoses and treatment outcomes in patients affected by TMJ disorders.

Effects of estradiol hormone in menopausal women on anterior disc displacement of temporomandibular joint

Anterior disc displacement is a condition when the articular disc is in the anterior normal position. Epidemiological research shows that the prevalence of TMD is higher in women than in men. Women have a dominant hormone that is not owned by men, the hormone estradiol. Estrogen receptors and the hormone progesterone are found in articular joints in humans. Joint structure, extracellular matrix remodeling, and bone volume modification can be affected by sexual hormones. It was thought to cause changes in connective tissue in the TMJ structure. This study aims to determine the effect of the level of the hormone estradiol in menopausal women on anterior temporal disc displacement of the temporomandibular joint. Subjects were 40 postmenopausal women who were examined for temporomandary joints. The diagnosis of anterior disc displacement was made using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC / TMD) method. Subjects were grouped into subjects with normal tempromandibular joints and subjects with anterior disc displacement. Estradiol hormone was examined by the immunoassay method. This study’s conclusion is estradiol hormone in menopausal women with anterior disc displacement is higher than menopausal women without anterior disc displacement.

Estrogen Selectively Enhances TMJ Disc but Not Knee Meniscus Matrix Loss

The preponderance of temporomandibular joint (TMJ) degenerative disorders in women and their early onset during reproductive years have implicated female sex hormones, particularly 17-β estradiol (E2), in the pathogenesis of these disorders. Nevertheless, the mechanisms by which E2 contributes to TMJ degenerative disorders and the reasons for its targeted effects on the TMJ but not other joints remain poorly understood. Here, we developed an ovariectomized mouse model in which systemic E2 concentrations mimicked those in cycling women, and we determined the effect of E2 on the targeted turnover of TMJ fibrocartilage matrix via E2-induced matrix metalloproteinases MMP9 and MMP13. Infusion of E2 and progesterone (P4; hormone control) over 7 d resulted in 5- and 8-fold greater serum E2 and P4 levels relative to controls, respectively, achieving systemic hormone levels similar to high baseline levels in cycling women. Administration of E2 but not P4 caused a significant loss of TMJ collagen and glycosaminoglycans, which was accompanied by amplification of ERα and specific increases in MMP9 and MMP13 expression. This dose of E2 had no effect on knee meniscus fibrocartilage, demonstrating the specificity of the degradative effect of E2. Dose-response experiments showed a greater sensitivity and a higher peak induction of MMP9 and MMP13 in TMJ fibrocartilaginous cells than knee meniscus cells to E2, providing an explanation for the differential responses of these tissues to E2. Using MMP9- and MMP13-null mice, we observed no discernible effects of each proteinase individually to E2-mediated TMJ matrix loss but noted a significant compensatory reciprocal induction of each MMP by E2 in the absence of the other. The redundancy in E2's induction of MMP9 and MMP13 suggests that the proteinases may together contribute to E2-mediated TMJ fibrocartilage loss. These results advance our understanding of E2-mediated upregulation of MMP9 and MMP13 on fibrocartilage matrix turnover targeted to the TMJ.

Evaluation of Association between the Severity of Temporomandibular Disorders and Quality of Sleep in a Selected Iranian Population

OBJECTIVES

Temporomandibular disorder (TMD), as a prevalent condition, has been reported to be related to changes in sleep quality. This study aims to assess the association between TMD severities and sleep quality in a selected Iranian population by the application of the Helkimo index and the Pittsburgh Sleep Quality Index (PSQI) questionnaire.

MATERIALS AND METHODS

This study comprised 50 non-TMD subjects and 150 TMD patients, which were equally selected from each TMD severity category. The study was conducted at the School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. The patients were first examined and categorized into four TMD severity groups according to the Helkimo index: Non-TMD, mild, moderate, and severe. Then, the patients completed the PSQI questionnaire, which was a standard version translated into Persian and adjusted for Iranian patients.

RESULTS

Comparison of mean PSQI scores of the four groups revealed a significant difference (P<0.001). Pairwise comparisons showed that the severe, moderate, and mild TMD groups and the control received the highest to the lowest PSQI scores (12.26±2.35, 8.20±1.92, 6.88±1.89, and 5.28±1.32, respectively). Similarly, regression analysis indicated that by controlling the effect of demographic variables, the mean PSQI significantly increased as TMD severity increased.

CONCLUSION

According to the results, all three categories of mild, moderate, and severe TMD patients showed poor quality of sleep in comparison with non-TMD controls. The higher the severity of the disease, the lower the sleep quality.

Association of risk factors with temporomandibular disorders in the Northern Finland Birth Cohort 1966

OBJECTIVE

To investigate the association between risk factors and pain-related symptoms and clinical signs of temporomandibular disorders (TMD) in Northern Finland Birth Cohort (NFBC) 1966.

MATERIAL AND METHODS

A total of 1962 subjects (1050 women, 912 men) attended the follow-up study. The questionnaires included the subjects' background information concerning living conditions and general health, socioeconomic factors, and dental health. The clinical examination was performed using the modified protocol of Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) presented at the International Association for Dental Research (IADR) Conference in 2010. Cross-tabulation, a chi-square test and Fisher's exact test were used to analyze differences between groups.

RESULTS

Female gender showed statistically significant association with symptoms and signs of TMD, while marital status, living conditions, and socioeconomic group showed no association. A strong association was found between self-reported health condition as well as general health problems [i.e. depression, migraine, fibromyalgia (FM), gastrointestinal diseases] and TMD pain-related symptoms and pain on palpation in the masticatory muscles and TMJs.

CONCLUSION

In conclusion, general health problems and female gender had a strong association with pain-related symptoms and clinical signs of TMD. These findings are important to take into account when diagnosing and treating TMD patients. Conversely to earlier presented results, no statistically significant association was shown here between marital status, living conditions or socioeconomic group and pain-related symptoms and clinical signs of TMD.

Association Between Polymorphisms in the Genes of Estrogen Receptors and the Presence of Temporomandibular Disorders and Chronic Arthralgia

PURPOSE

The high prevalence of painful temporomandibular disorders (TMDs) in women suggests that estrogen and its receptors play a fundamental etiologic role in the development of this joint pathology through complex action mechanisms. The aim of this study was to evaluate the possible association between polymorphisms in the ESR1 (estrogen receptor-1) and ESRRB (estrogen-related receptor-β) genes and the risk of simultaneous development of TMDs and pain in other joints in the body.

MATERIALS AND METHODS

All participants were clinically evaluated for the presence of TMD (Research Diagnostic Criteria for TMD) and asked about the presence of chronic joint pain. The control group consisted of 72 patients without TMD and without pain. Participants with arthralgia were divided into 3 groups: with muscular TMD (n = 42), with articular TMD (n = 16), and without TMD and with systemic arthralgia (n = 82). Eight single-nucleotide polymorphisms in the ESR1 (rs12154178, rs1884051, rs2273206, rs7774230) and ESRRB (rs1676303, rs4903399, rs10132091, rs7151924) genes were investigated. The χ² test and Student t and Mann-Whitney tests were used to assess the relevance of nominal and continuous variables, respectively. A P value less than .05 was considered significant.

RESULTS

The TT (timin/timin) genotype for the ESR1 (rs2273206) gene was strongly associated with the risk of developing muscle TMDs and temporomandibular joint pain (P = .04). For the ESRRB (rs1676303) gene, an association was observed between the CC (cytosine/cytosine) genotype and the presence of articular TMDs associated with other chronic arthralgia (P = .02). These results were confirmed by the increased risk of developing articular TMDs associated with the C allele (P = .04).

CONCLUSIONS

This study supports the hypothesis that changes in the ESR1 and ESRRB genes influence the presence of TMDs associated with chronic joint pain.

Temporomandibular disorders: Old ideas and new concepts

Background Temporomandibular disorders (TMD) is an umbrella term for pain and dysfunction involving the masticatory muscles and the temporomandibular joints (TMJs). TMD is the most common orofacial pain condition. Its prominent features include regional pain in the face and preauricular area, limitations in jaw movement, and noise from the TMJs during jaw movements. TMD affects up to 15% of adults and 7% of adolescents. Chronic pain is the overwhelming reason that patients with TMD seek treatment. TMD can associate with impaired general health, depression, and other psychological disabilities, and may affect the quality of life of the patient. Assessment Evaluations indicate that the recently published Diagnostic Criteria for TMD (DC/TMD) are reliable and valid. These criteria cover the most common types of TMD, which include pain-related disorders (e.g., myalgia, headache attributable to TMD, and arthralgia) as well as disorders associated with the TMJ (primarily disc displacements and degenerative disease). As peripheral mechanisms most likely play a role in the onset of TMD, a detailed muscle examination is recommended. The persistence of pain involves more central factors, such as sensitization of the supraspinal neurons and second-order neurons at the level of the spinal dorsal horn/trigeminal nucleus, imbalanced antinociceptive activity, and strong genetic predisposition, which also is included in DC/TMD. Conclusion The etiology is complex and still not clearly understood, but several biological and psychosocial risk factors for TMD have been identified. Several studies indicate that patients with TMD improve with a combination of noninvasive therapies, including behavior therapy, pharmacotherapy, physical therapy, and occlusal appliances. More stringently designed studies, however, are needed to assess treatment efficacy and how to tailor treatment to the individual patient.

Effects of bisphosphonates on mandibular condyle of ovariectomized osteoporotic rats using micro-ct and histomorphometric analysis

OBJECTIVE

To evaluate microarchitectural changes in condylar cartilage and associated subchondral bone after bisphosphonates treatment using an ovariectomized (OVX) osteoporosis rat model.

METHODS

Thirty six-month-old female Sprague-Dawley rats were randomly divided into sham, OVX, and risedronate (RIS)-treated groups. Both OVX and RIS groups received bilateral ovariectomy. OVX group was treated subcutaneously with saline, whereas RIS group received risedronate treatment (2.4 μg/kg) subcutaneously for 3 months. At the end of 3 months, animals were sacrificed and the entire condyles were harvested for micro-CT and histological analyses. Immunohistochemistry (IHC) was performed to assess the expression of type I/II collagen protein by semiquantitative imaging analysis.

RESULTS

Micro-CT analysis showed OVX group had significant condylar subchondral bone loss compared to sham as shown by significant decrease in bone volume fraction (P = 0.028), trabecular thickness (P = 0.041), and significant increase in trabecular spacing (P = 0.003). In RIS group, partial inhibition of OVX-induced bone loss was detected. HE staining showed proliferative layer of condylar cartilage reduced, while hypertrophic chondrocyte layer increased significantly in RIS group compared to sham and OVX groups. IHC showed reduced expression of Col I in both the OVX and RIS groups, whereas expression of Col II was reduced in the OVX group but increased in the RIS group.

CONCLUSION

Our findings suggest that systemic bisphosphonate treatment influences the structure and ossification of condylar cartilage and it has a dual action on condyle in a postmenopausal osteoporosis rat model which raises the concerns for the potential side effects of BPs on condyle to elder patients.

Mandibular Range of Movement and Pain Intensity in Patients with Anterior Disc Displacement without Reduction

OBJECTIVE

Temporomandibular disorders (TMD) are the most common source of orofacial pain of a non-dental origin. The study was performed to investigate the therapeutic effect of the conventional occlusal splint therapy and the physical therapy. The hypothesis tested was that the simultaneous use of occlusal splint and physical therapy is an effective method for treatment of anterior disc displacement without reduction.

MATERIALS AND METHODS

Twelve patients (mean age =30.5 y) with anterior disc displacement without reduction (according to RDC/TMD and confirmed by magnetic resonance imaging) were randomly allocated into 2 groups: 6 received stabilization splint (SS) and 6 received both physical therapy and stabilization splint (SS&PT). Treatment outcomes included pain-free opening (MCO), maximum assisted opening (MAO), path of mouth opening and pain as reported on visual analogue scale (VAS).

RESULTS

At baseline of treatment there were no significant differences among the groups for VAS scores, as well as for the range of mandibular movement. VAS scores improved significantly over time for the SS&PT group (F=28.964, p=0.0001, effect size =0.853) and SS group (F=8.794, p=0.001, effect size =0.638). The range of mouth opening improved significantly only in the SS&PT group (MCO: F=20.971, p=0.006; MAO: F=24.014, p=0.004) (Figure 2). Changes in path of mouth opening differ significantly between the groups (p=0.040). Only 1 patient in SS&PT group still presented deviations in mouth opening after completed therapy while in the SS group deviations were present in 5 patients after completed therapy.

CONCLUSION

This limited study gave evidence that during the treatment period lasting for 6 months, the simultaneous use of stabilization splint and physical therapy was more efficient in reducing deviations and improving range of mouth opening than the stabilization splint used alone. Both treatment options were efficient in reducing pain in patients with anterior disc displacement without reduction. Despite of objectively diagnosed disruption of temporomandibular joint anatomy, physiological function was regained.

Association between estrogen levels and temporomandibular disorders: a systematic literature review

Introduction

To evaluate whether the hypothesis that estrogen levels are associated with temporomandibular disorders (TMD) in humans can be confirmed or contradicted by available literature.

Material and methods

A systematic review based on the content of PubMed, Scopus, and Cochrane Library databases was performed. Studies were identified using a combination of key words ‘temporomandibular disorder’ and ‘estrogen’. Nine studies were included into our review.

Results

The relationship between estrogen levels and TMD was found in seven out of nine reviewed papers. Results from two papers suggest that a high estrogen level is associated with an increased prevalence of TMD. Five additional papers found a relationship between a low estrogen level and an increase in TMD pain. In considering the value of evidence and inconsistencies of results in the reviewed publications, we state that there is weak evidence to support the hypothesis that estrogen levels are associated with TMD.

Conclusions

Results of reviewed studies were divergent and sometimes contradictory. One possible explanation is that estrogen influences TMD pain processing differently than temporomandibular joints (TMJ) structures, as shown in many animal studies. Estrogen may influence TMD pain processing differently than TMJ structures. We suggest consideration of the dual action of estrogen when planning future studies on its association with TMD.

The influence of emotional state on the masticatory muscles function in the group of young healthy adults

Stress may affect the function of all the components of the masticatory system and may ultimately lead to differentiated symptoms and finally to systemic and structural dysfunctions. Objective. To determine the effect of stress on the masticatory muscles function in young healthy adults. Material and Methods. A total of 201 young, Angle's first class, healthy volunteers, 103 female and 98 male, in the age between 18 and 21 years were recruited into the study. All the participants underwent clinical examination according to the Slavicek scheme, questionnaire survey according to Perceived Stress Scale, and assessment of masticatory muscles function in central occlusion. Results. Symptoms of masticatory system dysfunction were found in the group of 86 subjects (46,24%). All the muscles activity in central occlusion was comparable in female and male groups. Mean values of masseters activities in the group of low stress subjects (75,52 µV ± 15,97) were statistically different from the groups with medium (82,43 µV ± 15,04) and high (81,33 ± 12,05) perceived stress (P < 0.05). Conclusion. Chronic stress may reveal or exacerbate symptoms of masticatory dysfunction.

Do the changes in muscle mass, muscle direction, and rotations of the condyles that occur after sagittal split advancement osteotomies play a role in the aetiology of progressive condylar resorption?

Changes in cross-sectional area (CSA), volume (indicating muscle strength), and direction of the masseter and medial pterygoid muscles after surgical mandibular advancement were measured, along with the rotation of the condyles after bilateral sagittal split osteotomies (BSSOs) to advance the mandible. Measurements were done on magnetic resonance images obtained before and 2 years after surgery. CSA and volume were measured in five short-face and seven long-face patients (five males, seven females). Muscle direction was calculated in eight short-face and eight long-face patients (eight males, eight females). Short-face patients underwent BSSO only; long-face patients underwent combined BSSO and Le Fort I osteotomies. The CSA and volume decreased significantly (mean 18%) in all patients after surgery. The postoperative muscle direction was significantly more vertical (9°) in long-face patients. Rotations of the proximal segments (condyles) were minimal after 2 years. The results of this study showed that, after BSSO advancement surgery, changes in the masseter and medial pterygoid muscles are not likely to cause increased pressure on the condyles and nor are the minimal rotations of the condyles. It is concluded that neither increased muscle traction nor condylar rotations can be held responsible for progressive condylar resorption after advancement BSSO.

Expression of estrogen receptors α and β in the trigeminal mesencephalic nucleus of adult women and men

Temporomandibular disorders are more prevalent in women than in men and phases of pain relate to the estrous cycle. Several studies described the location of estrogen receptors (ER) in the temporomandibular joint (TMJ), the masseteric muscles and cartilage, but it was unknown whether they are also expressed within the pseudounipolar neurons of the trigeminal mesencephalic nucleus, which receives direct sensory inputs from these structures. Therefore, we studied expression of ERα and ERβ protein in the trigeminal mesencephalic nucleus of ten human brains (five female/five male). Both receptors were uniformly expressed on neurons, but not other cell types within the target structure. Thus, sensory inputs from the TMJ and adjacent structures are likely to be modulated by estrogen at the level of the first sensory neuron which may underlie the well-known correlation of pain incidence and phases of the estrous cycle.

A cross-sectional study of the relationship between serum sexual hormone levels and internal derangement of temporomandibular joint

Temporomandibular disorders (TMD) are defined as clinical conditions that involve the masticatory muscles, temporomandibular joint (TMJ) or both. The aim of this study was to evaluate serum 17β-oestradiol and progesterone levels in menstruating women affected by internal derangement of the TMJ. A total of 142 women (mean age 30·2 ± 6·7) who referred to medical diagnostic laboratory of Iranian Academic Centre for Education, Culture and Research (ACECR), Mashhad Branch, were enrolled during 2007 and 2008. Forty-seven individuals had disc displacement with reduction (Group IIa) according to Research Diagnostic Criteria (RDC)/TMD Axis I diagnosis. Radioimmunoassay was used for the detection of serum 17β-oestradiol and progesterone levels in all 142 subjects. The mean progesterone level was significantly higher in control group (11·6 ± 10·4 ng mL(-1) ) compared to women with TMD (8·4 ± 6·8 ng mL(-1) , P = 0·03). No significant difference was found in two groups regarding 17β-oestradiol level. Lower progesterone level in women with TMD can suggest the more important role of this hormone in the development of the disorder.

Assessment of thickness and function of masticatory and cervical muscles in adults with and without temporomandibular disorders

OBJECTIVE

The aim of this study was to evaluate the maximal bite force (MBF), electromyographic (EMG) activity and thickness of the masseter, anterior part of the temporalis and sternocleidomastoid (SCM) muscles in a group of young adults with and without temporomandibular disorders (TMDs).

DESIGN

Nineteen individuals comprised the TMD group (6 males/13 females, aged 25.4±3.8 years), classified based on the Research Diagnostic Criteria for TMD (RDC/TMD), and 19 comprised the control group (6 males/13 females, aged 24.1±3.6 years). The MBF was determined with a transducer placed between the dental arches at the first molars level (N). The muscles were evaluated bilaterally at rest and during maximal voluntary clenching (MVC) by assessing EMG activity and performing ultrasonography (USG). The mean values of these measures for both sides of the mouth were used. The normality of the distributions was assessed by the Shapiro-Wilks test. Variables between groups and genders were compared using two-way factorial ANOVA test and correlated using the Spearman coefficient (α=0.05). Unpaired t test was used to compare variables between TMD subgroups. Logistic regression analysis was used to identify the variables associated with the presence of TMD.

RESULTS

MBF, EMG and USG data were similar among clinical groups and among TMD subgroups. The thickness of masseter and SCM muscles in the relaxed and clenching states were significantly higher in males than females. On the other hand, the EMG of the temporalis muscle in the rest state was significantly higher in females than males. Additionally, the MBF was positively correlated with the USG characteristics of masseter and SCM muscles, as well as with the EMG activity of masseter and temporalis muscles in the TMD group. In this group, there was also a positive correlation between the thickness of the masseter muscle and its activity. On the other hand, the thickness of the SCM muscle was negatively correlated with its activity. A lower MBF was independently associated with the presence of TMD.

CONCLUSIONS

Subjects with TMD exhibited similar values of MBF, thickness and electrical activity of masticatory and cervical muscles when compared with controls; positive correlations observed between these variables may suggest a muscular alteration in TMD patients and a co-activation of masticatory and cervical muscles during mandibular movement. This fact may also be confirmed by the negative association between bite forces and presence of TMD.

Physical therapy and anesthetic blockage for treating temporomandibular disorders: a clinical trial

Purpose: the aim of this study was to evaluate the use of physical therapy and anesthetic blockage of the auriculotemporal nerve as a treatment for temporomandibular joint disorders. Methods: the sample comprised of twenty patients with a diagnosis of disc displacement with/ without reduction and arthralgia according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD Axis I Group IIa, IIb and IIIa). Ten patients (group 1) underwent a cycle of eight anesthetic blockages of the auriculotemporal nerve with injections (1 per week) of 1 ml of bupivacaine 0.5% without vasoconstrictor for 8 weeks. The other 10 patients (group 2) received anesthetic blockage and physical therapy (massage and muscular stretching exercises). After the end of treatment all patients were evaluated at baseline, 1st week, 4th week and 2 months. The t-Student and F (ANOVA) tests were used for statistical analysis, with a significance rate of 5%. Results: there was a significant difference when both groups were compared according to VAS score (p=0.027). There was no significant difference for the other variables: MMO and jaw protrusion. Conclusion: the anesthetic blockage and physical therapy, when used together, are effective in the reduction of pain in patients with TMD.

Key words:Temporomandibular joint disorders, physical therapy, physiotherapy and nerve block, local anesthetic, bupivacaine.

Prevalence of symptoms indicative of temporomandibular disorders in adults: cross-sectional epidemiological investigations covering two decades

OBJECTIVES

The aims were (1) to study possible secular trends in the prevalence of temporomandibular disorder (TMD) symptoms in adults and (2) to analyse possible associations between TMD symptoms and background factors.

MATERIALS AND METHODS

The investigation has a repeated cross-sectional design. Three independent, randomly selected samples of ∼100 individuals in the age groups of 20, 30, 40, 50, 60 and 70 years, a total of 1704 subjects, participated in the Jönköping studies in 1983, 1993 and 2003. All the subjects were evaluated using a questionnaire and a structured interview relating to the presence of TMD symptoms. Associations between symptoms and the Anamnestic Dysfunction Index (Ai) as dependent variables and each of the independent variables, age group, gender, reported bruxism, trauma (1983), self-perceived health impairment and the year of investigation were analysed in binary logistic regression models.

RESULTS

The prevalence of the separate symptoms, apart from for TMJ clicking, did not vary to any statistically significant degree between the different examination years. However, the prevalence of recurrent headache in 20-year-old subjects rose remarkably in 2003 and an increase in the Ai I and Ai II for the whole population was observed during the 20-year period. Reported bruxism, which increased during the study period, and self-perceived health impairment were associated with most of the TMD symptoms and the Ai.

CONCLUSIONS

An increase in the prevalence of TMD symptoms expressed as Anamnestic Dysfunction Index I and II has been noted over a 20-year period.

Genetic polymorphisms in folate pathway enzymes, DRD4 and GSTM1 are related to temporomandibular disorder

Background

Temporomandibular disorder (TMD) is a multifactorial syndrome related to a critical period of human life. TMD has been associated with psychological dysfunctions, oxidative state and sexual dimorphism with coincidental occurrence along the pubertal development. In this work we study the association between TMD and genetic polymorphisms of folate metabolism, neurotransmission, oxidative and hormonal metabolism. Folate metabolism, which depends on genes variations and diet, is directly involved in genetic and epigenetic variations that can influence the changes of last growing period of development in human and the appearance of the TMD.

Methods

A case-control study was designed to evaluate the impact of genetic polymorphisms above described on TMD. A total of 229 individuals (69% women) were included at the study; 86 were patients with TMD and 143 were healthy control subjects. Subjects underwent to a clinical examination following the guidelines by the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Genotyping of 20 Single Nucleotide Polymorphisms (SNPs), divided in two groups, was performed by multiplex minisequencing preceded by multiplex PCR. Other seven genetic polymorphisms different from SNPs (deletions, insertions, tandem repeat, null genotype) were achieved by a multiplex-PCR. A chi-square test was performed to determine the differences in genotype and allelic frequencies between TMD patients and healthy subjects. To estimate TMD risk, in those polymorphisms that shown significant differences, odds ratio (OR) with a 95% of confidence interval were calculated.

Results

Six of the polymorphisms showed statistical associations with TMD. Four of them are related to enzymes of folates metabolism: Allele G of Serine Hydoxymethyltransferase 1 (SHMT1) rs1979277 (OR = 3.99; 95%CI 1.72, 9.25; p = 0.002), allele G of SHMT1 rs638416 (OR = 2.80; 95%CI 1.51, 5.21; p = 0.013), allele T of Methylentetrahydrofolate Dehydrogenase (MTHFD) rs2236225 (OR = 3.09; 95%CI 1.27, 7.50; p = 0.016) and allele A of Methionine Synthase Reductase (MTRR) rs1801394 (OR = 2.35; 95CI 1.10, 5.00; p = 0.037). An inflammatory oxidative stress enzyme, Gluthatione S-Tranferase Mu-1(GSTM1), null allele (OR = 2.21; 95%CI 1.24, 4.36; p = 0.030) and a neurotransmission receptor, Dopamine Receptor D4 (DRD4), long allele of 48 bp-repeat (OR = 3.62; 95%CI 0.76, 17.26; p = 0.161).

Conclusions

Some genetic polymorphisms related to folates metabolism, inflammatory oxidative stress, and neurotransmission responses to pain, has been significantly associated to TMD syndrome

Osteoimmunopathology in HIV/AIDS: A Translational Evidence-Based Perspective

Infection with the human immunodeficiency virus-1 (HIV) and the resulting acquired immune deficiency syndrome (AIDS) alter not only cellular immune regulation but also the bone metabolism. Since cellular immunity and bone metabolism are intimately intertwined in the osteoimmune network, it is to be expected that bone metabolism is also affected in patients with HIV/AIDS. The concerted evidence points convincingly toward impaired activity of osteoblasts and increased activity of osteoclasts in patients with HIV/AIDS, leading to a significant increase in the prevalence of osteoporosis. Research attributes these outcomes in part at least to the ART, PI, and HAART therapies endured by these patients. We review and discuss these lines of evidence from the perspective of translational clinically relevant complex systematic reviews for comparative effectiveness analysis and evidence-based intervention on a global scale.